The invention described herein was made in the performance of work under a NASA contract NAS8-01078 and is subject to the provisions of Public Law 96-517 (35 USC 202) in which the contractor has elected not to retain title.
1. Field of the Invention
This invention is directed towards the containment of charged particles using static and rotating magnetic and electric fields in a high vacuum.
2. Description of the Related Art
The containment of highly reactive charged particles cannot be done by using strictly mechanical means as contact between the walls of a containment vessel and the particles to be contained would destroy the containment vessel or annihilate the particle being contained. Instead of using mechanical means for containment of particles, electric and magnetic fields interacting with the charged particles are used to redirect the charged particles away from the containment vessel. Thus, containment with electric and magnetic fields depends on the electrical charge of the the particle to be contained. It is the electrical charge of the particle that reacts with electric and magnetic fields present within the containment vessel to redirect particle motion away from the walls of the containment vessel, preserving both the particle and the vessel. One example of reactive particles to be contained away from the walls of a containment vessel is antimatter, such as negatively charged antiprotons. A convenient experimental equivalent to antiprotons are their xe2x80x9cnormal matterxe2x80x9d counter part, the hydrogen ion H+, more readily available and less reactive.
Antiprotons are similar to protons, but have a xe2x88x921 electrical charge, and a reversal of spin direction. The interest in containing antiprotons comes from the reaction of protons with antiprotons. This reaction has the highest potential specific energy density of any chemical or nuclear reaction, in the order of 108 Mjoules/gram. Harnessing this concentrated energy in a matter-antimatter engine minimizes the amount fuel to be carried by a space craft. In order to benefit from the high energy density of this reaction, it is necessary to contain and manipulate antiprotons for delivery at proper times and quantities to the matter-antimatter engine for controlled energy release to be converted to thrust by the engine.
Antiprotons are contained in a cloud residing within a containment vessel. The cloud is a collection of negatively charged antiprotons. The antiproton cloud cannot approach the vessel walls because of the spontaneous antiproton reaction with protons, part of the atomic make-up of any containment vessel wall. Thus, the antiproton cloud has to be directed away from the containment walls using electric and magnetic fields that interact with the cloud using well known electromagnetic forces. The containment vessel has an internal ultra high vacuum to minimize proton anti-proton reactions with background gas molecules.
Certain terms are used to describe charged particles that react with magnetic and electric fields to alter their motion within these fields. A plasma is an ionized gas composed of ions and/or electrons.Ions are atoms, group of atoms, or molecule(s) that have acquired a net electric charge by gaining electrons or losing electrons.A H+ ion, a proton, is a stable particle, having a positive +1 charge, in the Baryon family and a mass 1836 times that of an electron. Stripping a hydrogen atom of its electron will yield a positively charged (+1) proton, a preferred experimental substitute for an antiproton.
The containment of antiprotons has been discussed in the prior art. U.S. Pat. No. 6,414,331 to Smith et al. discusses a containment means for transporting and storing antiprotons, and is incorporated herein in its entirety by reference. The present invention improves over the ""331 patent by facilitating longer charged particle containment times and densities.
Other patents, such as U.S. Pat. No. 4,540,884 to Stafford at al, U.S. Pat. No. 5,469,323 to Kanayama, and U.S. Pat. No. 5,629,519 to Palermo describe an apparatus for short term containment times of charged particles.
A containment apparatus for containing a cloud of charged particles comprises a cylindrical vacuum chamber having a longitudinal axis, and an outer surface. Within the vacuum chamber is a containment region. A magnetic field is aligned with the longitudinal axis of the vacuum chamber. The magnetic field is time invariant and uniform in strength over the containment region.
An electric field is also aligned with the longitudinal axis of the vacuum chamber. The electric field is time invariant, and forms a potential well over the containment region. One or more means are disposed around the cloud of charged particles for inducing a rotating electric field internal to said vacuum chamber. The rotating electric field imparts energy to the charged particles within the containment region and compresses the cloud of particles. The rotating electric field can also expand instead of compress the cloud of particles depending on its rotating direction.
The means disposed around the outer surface of the vacuum chamber for inducing a rotating electric field are four or more segments forming a segmented ring, the segments conforming to the outer surface of the vacuum chamber. Each of the segments is energized by a separate alternating voltage. The sum of the voltages establishes the rotating field.
When four segments form a ring, the rotating field is obtained by a signal generator applying a sinusoidal signal phase delayed by 0, 90, 180 and 270 degrees in sequence to the four segments.